Where would you mount the injector bungs on this?

[JeffMcKC]

I would just make a spacer out of aluminum and bore the holes in it for bungs, and use the carb for the TB. It could be a couple inches tall if needed to get some angle to it.

[dieselgeek]

two or more are a good idea because, in a throttle body EFI situation you want to get as close to a continuous stream of incoming fuel as possible. I'd go with 2-4 injectors and run them in alternating pattern, multiple squirts per cycle. I've put a TBI on that same engine once already. It idled at 300rpm happy as a clam, lol.

[TheSilverBuick]

The barrel is so narrow I don't know how you would avoid that anyways, plus if you set it up for alternating firing (common) then they would take turns. Or you could always stage them so that one only comes on above a certain rpm or load, of course that is a tad more difficult to tune.

[Caveman Tony]

Why pointed at each other?

Wouldn't they just smash the spray patterns together and make big fat globs of fuel?

[TheSilverBuick]

Two, pointed at each other on a chunk of pipe that replaces the carburetor. Or if you don't care about the carb, drill out the sides of it and glue injector bungs directly into it. Don't worry about a TPS sensor, run the accel enrichment off the vacuum. Just get a coolant and air temp sensor and call it good. Tune it by your nose and how it runs unless you can borrow an LC1 or want to try your hand at a $20 narrowband sensor (which might work decent for this application).

[Caveman Tony]

So I google'd some formulae, (plural?) and came up with some interesting numbers...

218 c.i. = roughly 215 cfm req'd at around no more than 4000 rpm. This thing ain't a screamer..

Est HP? Meh.. Straight six flathead? 100. And that's being generous. Probly more like 80.

**Edit** wikipedia says the 46-49 I-6's had a rated 95 hp. Wheeeeee.... so it's actually around a 29lb/hr...

Formula for injector sizing: HP x .50 / # of injectors x .80

sooo.... 100 x .50 / 1 injector x .80 = 50 / 1.6 = 31.25 lb/hr injector if I run just one.

In a confined space, that might be just as well.


Thoughts?

Would you put one on a tubular piece above the original intake? Or two, opposing each other? Don't really think three smaller ones in each branch of the lower intake would be feasible, as the distribution would be way unequal. (center runners are way shorter, different flow, etc...)

[TheSilverBuick]

19lb/hr are about as small as you can go I think. They come in all sorts of stock applications from the late-80's through late 90's. V8 and V6's and probably most 4 cylinders.

[Caveman Tony]

For a low-rpm 218ci, how big of an injector would you go with? Not a lot of cfm going through there...

[TheSilverBuick]

For dead nuts stupid simple you could probably just make a tube that bolts in place of the carb and stick two injectors in it and it'll probably still function better than the carb, or at least give you less cold start and maintenance trouble.

[Caveman Tony]

Oh, and it's a 218ci flathead-6 Chrysler industrial engine, one of the 'small block' of that family.

They also came in a bunch of other sizes...

http://en.wikipedia.org/wiki/Chrysler_Flathead_engine

[Caveman Tony]

I actually started down the K-car throttle body route... and it is appetizing, except that the K-car piece is too wide. Doesn't fit behind the cowling/engine cover.

For that to fit, I would have to build an offset intake above the spark plugs over the center of the engine with a weird "S" curved intake down to the original intake. And it also has to fit under the fuel tank, which is directly above the center of the engine.

I actually think building a bolt-on plenum with injectors on the sides above the original intake wouldn't be such a bad setup. If I did that out of something like 3x4 square steel, would it cause issues with vapor lock from heat transfer?

This tractor actually runs great on level ground.... only problem is, I don't live on level ground. Or anywhere near it.

[anotheridiot]

Oh it is a six, I don't know what I was thinking.

The simplest thing would be to get a 1bbl TBI from an old 4-cyinder car (k car?). In any case, I think one injector per cylinder pair would be enough for this application.

I kind of like BBR's idea, lol.

Yeah. my first answer was right in front of the spark plug lol.

[milner351]

does anyone make a pipe thread injector bung?

surely something like that wouldn't take much for a somewhat talented lathe operator to churn out - probably better out of steel or brass/bronze than aluminum. NPT on the outside, injector o-ring seal on the inside with a chamfer at the top to ease the o-ring into position.

Given the poor distribution of the inline 6 with centrally located carb - injectors aimed at each port would be a huge improvement - even if they're "batch fired" - don't you think Randal?

[TheSilverBuick]

Oh it is a six, I don't know what I was thinking.

The simplest thing would be to get a 1bbl TBI from an old 4-cyinder car (k car?). In any case, I think one injector per cylinder pair would be enough for this application.

I kind of like BBR's idea, lol.

[anotheridiot]

awesome old motor.straight shots to outside cylinders, but each intake port is feeding two cylinders right? Can you use three injectors and have them fire twice for the separate shot for 1 and 2? If you can use the same injector to give fuel twice you can go straight in the end two, maybe machine a bigger tube thru the air box on the manifold to place the middle injector at the same distance. It looks like you already have a throttle body though, just take off the top third of the carburetor.